What determines when a Mirage spot becomes Available?

I know they come and go but what determines this. Are they timed Locations?

Pleaselog inorregisterto add a comment.

Since ORAS is new, I will say what I know about Mirage spots. There’s been some debate about the randomness of Mirage spots, but ultimately the Serebii list is pretty complete.

Different legendaries require different conditions to appear.

Cresselia - can be random, can be obtained from streetpass encountersZekrom/ Reshiram - have a Pokemon at L100 in your partyKyurem - have Reshiram and Zekrom in your partyLake trio - have 3 Pokemon with max happiness in your party (also limited to certain times; see Serebii link below)Sword trio - have 3 Pokemon with max EVs in your party (also limited to certain days of the week; see Serebii link below)Dialga/ Palkia - have Lake Trio in your party (Dialga for AS, Palkia for OR)Giratina - have Dialga and Palkia in your partyTornadus/ Thundurus - have Castform in your partyLandorus - have Tornadus and Thundurus in your partyDogs trio - have Lugia and Ho-Oh in your party

As for the islands, it appears that they’re random. Also note that if you save on a mirage island/ cave/ path (i.e. one that doesn’t give a legendary, just other normal Pokemon), and open your game the next day, you will still be on that island and catch Pokemon there. Once you fly/ soar to leave, the island will disappear and a new one will appear for the day.

Also, turning on Streepass will you give more islands that do not hold legendaries (except Cresselia).

Serebii - Mirage spotsSerebii - ORAS legendaries (shows how to get Lugia & Ho-Oh)

Mirage Islands are not timed events.The only thing known about them so far is that

A Mirage Island can appear daily, or it may not appear, being replaced with a Mirage Forest, Mirage Cave, or Mirage Mountain. More Mirage Spots can appear via StreetPass.

Source